51
|
Ascarosides coordinate the dispersal of a plant-parasitic nematode with the metamorphosis of its vector beetle. Nat Commun 2016; 7:12341. [PMID: 27477780 PMCID: PMC4974635 DOI: 10.1038/ncomms12341] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 06/23/2016] [Indexed: 11/24/2022] Open
Abstract
Insect vectors are required for the transmission of many species of parasitic nematodes, but the mechanisms by which the vectors and nematodes coordinate their life cycles are poorly understood. Here, we report that ascarosides, an evolutionarily conserved family of nematode pheromones, are produced not only by a plant-parasitic nematode, but also by its vector beetle. The pinewood nematode and its vector beetle cause pine wilt disease, which threatens forest ecosystems world-wide. Ascarosides secreted by the dispersal third-stage nematode LIII larvae promote beetle pupation by inducing ecdysone production in the beetle and up-regulating ecdysone-dependent gene expression. Once the beetle develops into the adult stage, it secretes ascarosides that attract the dispersal fourth-stage nematode LIV larvae, potentially facilitating their movement into the beetle trachea for transport to the next pine tree. These results demonstrate that ascarosides play a key role in the survival and spread of pine wilt disease. Many species of nematodes use pheromones called ascarosides to coordinate their behaviour and development. Here, Zhao et al. demonstrate that the beetle vector of the pinewood nematode (Bursaphelenchus xylophilus) also uses and responds to ascarosides in its interactions with the nematodes.
Collapse
|
52
|
Large EE, Xu W, Zhao Y, Brady SC, Long L, Butcher RA, Andersen EC, McGrath PT. Selection on a Subunit of the NURF Chromatin Remodeler Modifies Life History Traits in a Domesticated Strain of Caenorhabditis elegans. PLoS Genet 2016; 12:e1006219. [PMID: 27467070 PMCID: PMC4965130 DOI: 10.1371/journal.pgen.1006219] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 07/01/2016] [Indexed: 11/20/2022] Open
Abstract
Evolutionary life history theory seeks to explain how reproductive and survival traits are shaped by selection through allocations of an individual’s resources to competing life functions. Although life-history traits evolve rapidly, little is known about the genetic and cellular mechanisms that control and couple these tradeoffs. Here, we find that two laboratory-adapted strains of C. elegans descended from a single common ancestor that lived in the 1950s have differences in a number of life-history traits, including reproductive timing, lifespan, dauer formation, growth rate, and offspring number. We identified a quantitative trait locus (QTL) of large effect that controls 24%–75% of the total trait variance in reproductive timing at various timepoints. Using CRISPR/Cas9-induced genome editing, we show this QTL is due in part to a 60 bp deletion in the 3’ end of the nurf-1 gene, which is orthologous to the human gene encoding the BPTF component of the NURF chromatin remodeling complex. Besides reproduction, nurf-1 also regulates growth rate, lifespan, and dauer formation. The fitness consequences of this deletion are environment specific—it increases fitness in the growth conditions where it was fixed but decreases fitness in alternative laboratory growth conditions. We propose that chromatin remodeling, acting through nurf-1, is a pleiotropic regulator of life history trade-offs underlying the evolution of multiple traits across different species. Sex and death are two fundamental concerns of each organism. These traits evolve rapidly in natural populations as animals seek to maximize their fitness in a given environment. For example, in mammals, lifespan, size, and fecundity vary over two order of magnitude. A key observation of evolutionary life history theory is the recognition that there are limited amount of resources available, which creates tradeoffs between competing life functions. By studying a domesticated strain of C. elegans, we identify a beneficial mutation that regulates a number of life history tradeoffs. This mutation affects a subunit of the NURF chromatin remodeling complex. Our work suggests that NURF is a master regulator of life history tradeoffs through epigenetic regulation, and a target of evolution.
Collapse
Affiliation(s)
- Edward E. Large
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Wen Xu
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Yuehui Zhao
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Shannon C. Brady
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Lijiang Long
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Rebecca A. Butcher
- Department of Chemistry, University of Florida, Gainesville, Florida, United States of America
| | - Erik C. Andersen
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Patrick T. McGrath
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- * E-mail:
| |
Collapse
|
53
|
Ow MC, Hall SE. A Method for Obtaining Large Populations of Synchronized Caenorhabditis elegans Dauer Larvae. Methods Mol Biol 2016; 1327:209-19. [PMID: 26423977 DOI: 10.1007/978-1-4939-2842-2_15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
The C. elegans dauer is an attractive model with which to investigate fundamental biological questions, such as how environmental cues are sensed and are translated into developmental decisions through a series of signaling cascades that ultimately result in a transformed animal. Here we describe a simple method of using egg white plates to obtain highly synchronized purified dauers that can be used in downstream applications requiring large quantities of dauers or postdauer animals.
Collapse
Affiliation(s)
- Maria C Ow
- Department of Biology, Syracuse University, 107 College Place, Room 110, Syracuse, NY, 13244, USA
| | - Sarah E Hall
- Department of Biology, Syracuse University, 107 College Place, Room 110, Syracuse, NY, 13244, USA.
| |
Collapse
|
54
|
BLIMP-1/BLMP-1 and Metastasis-Associated Protein Regulate Stress Resistant Development in Caenorhabditis elegans. Genetics 2016; 203:1721-32. [PMID: 27334271 DOI: 10.1534/genetics.116.190793] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 06/14/2016] [Indexed: 01/17/2023] Open
Abstract
Environmental stress triggers multilevel adaptations in animal development that depend in part on epigenetic mechanisms. In response to harsh environmental conditions and pheromone signals, Caenorhabditis elegans larvae become the highly stress-resistant and long-lived dauer. Despite extensive studies of dauer formation pathways that integrate specific environmental cues and appear to depend on transcriptional reprogramming, the role of epigenetic regulation in dauer development has remained unclear. Here we report that BLMP-1, the BLIMP-1 ortholog, regulates dauer formation via epigenetic pathways; in the absence of TGF-β signaling (in daf-7 mutants), lack of blmp-1 caused lethality. Using this phenotype, we screened 283 epigenetic factors, and identified lin-40, a homolog of metastasis-associate protein 1 (MTA1) as an interactor of BLMP-1 The interaction between LIN-40 and BLMP-1 is conserved because mammalian homologs for both MTA1 and BLIMP-1 could also interact. From microarray studies, we identified several downstream target genes of blmp-1: npr-3, nhr-23, ptr-4, and sams-1 Among them S-adenosyl methionine synthase (SAMS-1), is the key enzyme for production of SAM used in histone methylation. Indeed, blmp-1 is necessary for controlling histone methylation level in daf-7 mutants, suggesting BLMP-1 regulates the expression of SAMS-1, which in turn may regulate histone methylation and dauer formation. Our results reveal a new interaction between BLMP-1/BLIMP-1 and LIN-40/MTA1, as well as potential epigenetic downstream pathways, whereby these proteins cooperate to regulate stress-specific developmental adaptations.
Collapse
|
55
|
Abstract
DNA does not make phenotypes on its own. In this volume entitled "Genes and Phenotypic Evolution," the present review draws the attention on the process of phenotype construction-including development of multicellular organisms-and the multiple interactions and feedbacks between DNA, organism, and environment at various levels and timescales in the evolutionary process. First, during the construction of an individual's phenotype, DNA is recruited as a template for building blocks within the cellular context and may in addition be involved in dynamical feedback loops that depend on the environmental and organismal context. Second, in the production of phenotypic variation among individuals, stochastic, environmental, genetic, and parental sources of variation act jointly. While in controlled laboratory settings, various genetic and environmental factors can be tested one at a time or in various combinations, they cannot be separated in natural populations because the environment is not controlled and the genotype can rarely be replicated. Third, along generations, genotype and environment each have specific properties concerning the origin of their variation, the hereditary transmission of this variation, and the evolutionary feedbacks. Natural selection acts as a feedback from phenotype and environment to genotype. This review integrates recent results and concrete examples that illustrate these three points. Although some themes are shared with recent calls and claims to a new conceptual framework in evolutionary biology, the viewpoint presented here only means to add flesh to the standard evolutionary synthesis.
Collapse
Affiliation(s)
- M-A Félix
- Institut de Biologie Ecole Normale Supérieure, CNRS, Paris, France.
| |
Collapse
|
56
|
Guo H, La Clair JJ, Masler EP, O'Doherty G, Xing Y. De Novo Asymmetric Synthesis and Biological Analysis of the Daumone Pheromones in Caenorhabditis elegans and in the Soybean Cyst Nematode Heterodera glycines. Tetrahedron 2016; 72:2280-2286. [PMID: 29445247 PMCID: PMC5809136 DOI: 10.1016/j.tet.2016.03.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The de novo asymmetric total syntheses of daumone 1, daumone 3 along with 5 new analogs are described. The key steps of our approach are: the diastereoselective palladium catalyzed glycosylation reaction; the Noyori reduction of 2-acetylfuran and an ynone, which introduce the absolute stereochemistry of the sugar and aglycon portion of daumone; and an Achmatowicz rearrangement, an epoxidation and a ring opening installing the remaining asymmetry of daumone. The synthetic daumones 1 and 3 as well as related analogs were evaluated for dauer activity in C. elegans and for effects on hatching of the related nematode H. glycines. This data provides additional structure activity relationships (SAR) that further inform the study of nematode signaling.
Collapse
Affiliation(s)
- Haibing Guo
- School of Nuclear Technology and Chemistry & Life Science, Hubei University of Science and Technology, Xianning 437100, China
| | - James J La Clair
- Xenobe Research Institute, P. O. Box 3052, San Diego, CA 92163-1052, USA
| | - Edward P Masler
- Nematology Laboratory, USDA-ARS-NEA, Beltsville MD 20705, USA
| | - George O'Doherty
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, USA
| | - Yalan Xing
- Department of Chemistry, William Paterson University, 300 Pompton Rd, Wayne, NJ 07470, USA
| |
Collapse
|
57
|
Identification of a dTDP-rhamnose biosynthetic pathway that oscillates with the molting cycle in Caenorhabditis elegans. Biochem J 2016; 473:1507-21. [PMID: 27009306 PMCID: PMC4888466 DOI: 10.1042/bcj20160142] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 03/23/2016] [Indexed: 01/08/2023]
Abstract
The rhamnose biosynthetic pathway, which is highly conserved across nematode species, was characterized in the nematode Caenorhabditis elegans. The pathway is up-regulated before each larval molt, suggesting that rhamnose biosynthesis plays a role in cuticle or surface coat synthesis. L-Rhamnose is a common component of cell-wall polysaccharides, glycoproteins and some natural products in bacteria and plants, but is rare in fungi and animals. In the present study, we identify and characterize a biosynthetic pathway for dTDP-rhamnose in Caenorhabditis elegans that is highly conserved across nematode species. We show that RML-1 activates glucose 1-phosphate (Glc-1-P) in the presence of either dTTP or UTP to yield dTDP-glucose or UDP-glucose, respectively. RML-2 is a dTDP-glucose 4,6-dehydratase, converting dTDP-glucose into dTDP-4-keto-6-deoxyglucose. Using mass spectrometry and NMR spectroscopy, we demonstrate that coincubation of dTDP-4-keto-6-deoxyglucose with RML-3 (3,5-epimerase) and RML-4 (4-keto-reductase) produces dTDP-rhamnose. RML-4 could only be expressed and purified in an active form through co-expression with a co-regulated protein, RML-5, which forms a complex with RML-4. Analysis of the sugar nucleotide pool in C. elegans established the presence of dTDP-rhamnose in vivo. Targeting the expression of the rhamnose biosynthetic genes by RNAi resulted in significant reductions in dTDP-rhamnose, but had no effect on the biosynthesis of a closely related sugar, ascarylose, found in the ascaroside pheromones. Therefore, the rhamnose and ascarylose biosynthetic pathways are distinct. We also show that transcriptional reporters for the rhamnose biosynthetic genes are expressed highly in the embryo, in the hypodermis during molting cycles and in the hypodermal seam cells specifically before the molt to the stress-resistant dauer larval stage. These expression patterns suggest that rhamnose biosynthesis may play an important role in hypodermal development or the production of the cuticle or surface coat during molting.
Collapse
|
58
|
Aprison EZ, Ruvinsky I. Sex Pheromones of C. elegans Males Prime the Female Reproductive System and Ameliorate the Effects of Heat Stress. PLoS Genet 2015; 11:e1005729. [PMID: 26645097 PMCID: PMC4672928 DOI: 10.1371/journal.pgen.1005729] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 11/16/2015] [Indexed: 12/26/2022] Open
Abstract
Pheromones are secreted molecules that mediate animal communications. These olfactory signals can have substantial effects on physiology and likely play important roles in organismal survival in natural habitats. Here we show that a blend of two ascaroside pheromones produced by C. elegans males primes the female reproductive system in part by improving sperm guidance toward oocytes. Worms have different physiological responses to different ratios of the same two molecules, revealing an efficient mechanism for increasing coding potential of a limited repertoire of molecular signals. The endogenous function of the male sex pheromones has an important side benefit. It substantially ameliorates the detrimental effects of prolonged heat stress on hermaphrodite reproduction because it increases the effectiveness with which surviving gametes are used following stress. Hermaphroditic species are expected to lose female-specific traits in the course of evolution. Our results suggest that some of these traits could have serendipitous utility due to their ability to counter the effects of stress. We propose that this is a general mechanism by which some mating-related functions could be retained in hermaphroditic species, despite their expected decay. The Caenorhabditis elegans metabolome contains over a hundred ascaroside molecules. Most of them have no known function, or no function at all, but some act as pheromones. Two of these molecules, ascr#10 and ascr#3, are produced in different proportions by males and hermaphrodites. We report that when a hermaphrodite senses a male-specific mixture of these molecules, it changes several aspects of its reproductive physiology, including signaling that guides sperm toward oocytes. During evolution from an ancestor that had both males and females, C. elegans hermaphrodites lost several female-specific traits, but their reproductive system retained the ability to respond to male pheromones. This greatly aids them during recovery from heat stress. We suggest that serendipitous side benefits of female-specific traits could be a general cause of their retention during evolution.
Collapse
Affiliation(s)
- Erin Z. Aprison
- Department of Ecology and Evolution, The University of Chicago, Chicago, Illinois, United States of America
| | - Ilya Ruvinsky
- Department of Ecology and Evolution, The University of Chicago, Chicago, Illinois, United States of America
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, United States of America
- * E-mail:
| |
Collapse
|
59
|
Sommer RJ, Mayer MG. Toward a Synthesis of Developmental Biology with Evolutionary Theory and Ecology. Annu Rev Cell Dev Biol 2015; 31:453-71. [DOI: 10.1146/annurev-cellbio-102314-112451] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ralf J. Sommer
- Department for Evolutionary Biology, Max-Planck Institute for Developmental Biology, 72076 Tübingen, Germany;
| | - Melanie G. Mayer
- Department for Evolutionary Biology, Max-Planck Institute for Developmental Biology, 72076 Tübingen, Germany;
| |
Collapse
|
60
|
Abstract
Food availability determines developmental rate, behavior, and survival of animals. Animals that enter diapause or hibernate in response to lack of food have a double advantage: they are able to adapt to environmental and cellular challenges and survive to these challenges for a prolonged time. The metabolic and physiological adaptations that make possible diapause and hibernation also provide a favorable cellular environment for tissue protection. This review highlights the benefits of dormancy on neuronal protection in the model organism Caenorhabditis elegans and small mammals such as squirrels. Additionally, I discuss the link between metabolic restructuring occurring in diapause and changes in gene expression with the increased capacity of diapausing animals to protect neurons from degeneration and potentially foster their regeneration.
Collapse
Affiliation(s)
- Andrea Calixto
- Center for Genomics and Bioinformatics, Faculty of Sciences, Universidad Mayor, Santiago, Chile.
| |
Collapse
|
61
|
Richter K. daf-41/p23: A Small Protein Heating Up Lifespan Regulation. PLoS Genet 2015; 11:e1005188. [PMID: 26147370 PMCID: PMC4492944 DOI: 10.1371/journal.pgen.1005188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Klaus Richter
- Department Chemie, Technische Universität München, Garching, Germany
- Center for Integrated Protein Science Munich CIPS, Munich, Germany
- * E-mail:
| |
Collapse
|
62
|
von Reuss SH, Schroeder FC. Combinatorial chemistry in nematodes: modular assembly of primary metabolism-derived building blocks. Nat Prod Rep 2015; 32:994-1006. [PMID: 26059053 PMCID: PMC4884655 DOI: 10.1039/c5np00042d] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The nematode Caenorhabditis elegans was the first animal to have its genome fully sequenced and has become an important model organism for biomedical research. However, like many other animal model systems, its metabolome remained largely uncharacterized, until recent investigations demonstrated the importance of small molecule-based signalling cascades for virtually every aspect of nematode biology. These studies have revealed that nematodes are amazingly skilled chemists: using simple building blocks from conserved primary metabolism and a strategy of modular assembly, C. elegans and other nematode species create complex molecular architectures to regulate their development and behaviour. These nematode-derived modular metabolites (NDMMs) are based on the dideoxysugars ascarylose or paratose, which serve as scaffolds for attachment of moieties from lipid, amino acid, carbohydrate, citrate, and nucleoside metabolism. Mutant screens and comparative metabolomics based on NMR spectroscopy and MS have so-far revealed several 100 different ascarylose ("ascarosides") and a few paratose ("paratosides") derivatives, many of which represent potent signalling molecules that can be active at femtomolar levels, regulating development, behaviour, body shape, and many other life history traits. NDMM biosynthesis appears to be carefully regulated as assembly of different modules proceeds with very high specificity. Preliminary biosynthetic studies have confirmed the primary metabolism origin of some NDMM building blocks, whereas the mechanisms that underlie their highly specific assembly are not understood. Considering their functions and biosynthetic origin, NDMMs represent a new class of natural products that cannot easily be classified as "primary" or "secondary". We believe that the identification of new variants of primary metabolism-derived structures that serve important signalling functions in C. elegans and other nematodes provides a strong incentive for a comprehensive re-analysis of metabolism in higher animals, including humans.
Collapse
Affiliation(s)
- Stephan H. von Reuss
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Jena, Germany
| | - Frank C. Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| |
Collapse
|
63
|
Acyl-CoA oxidase complexes control the chemical message produced by Caenorhabditis elegans. Proc Natl Acad Sci U S A 2015; 112:3955-60. [PMID: 25775534 DOI: 10.1073/pnas.1423951112] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Caenorhabditis elegans uses ascaroside pheromones to induce development of the stress-resistant dauer larval stage and to coordinate various behaviors. Peroxisomal β-oxidation cycles are required for the biosynthesis of the fatty acid-derived side chains of the ascarosides. Here we show that three acyl-CoA oxidases, which catalyze the first step in these β-oxidation cycles, form different protein homo- and heterodimers with distinct substrate preferences. Mutations in the acyl-CoA oxidase genes acox-1, -2, and -3 led to specific defects in ascaroside production. When the acyl-CoA oxidases were expressed alone or in pairs and purified, the resulting acyl-CoA oxidase homo- and heterodimers displayed different side-chain length preferences in an in vitro activity assay. Specifically, an ACOX-1 homodimer controls the production of ascarosides with side chains with nine or fewer carbons, an ACOX-1/ACOX-3 heterodimer controls the production of those with side chains with seven or fewer carbons, and an ACOX-2 homodimer controls the production of those with ω-side chains with less than five carbons. Our results support a biosynthetic model in which β-oxidation enzymes act directly on the CoA-thioesters of ascaroside biosynthetic precursors. Furthermore, we identify environmental conditions, including high temperature and low food availability, that induce the expression of acox-2 and/or acox-3 and lead to corresponding changes in ascaroside production. Thus, our work uncovers an important mechanism by which C. elegans increases the production of the most potent dauer pheromones, those with the shortest side chains, under specific environmental conditions.
Collapse
|
64
|
Diaz SA, Viney M. The evolution of plasticity of dauer larva developmental arrest in the nematode Caenorhabditis elegans. Ecol Evol 2015; 5:1343-53. [PMID: 25859338 PMCID: PMC4377276 DOI: 10.1002/ece3.1436] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 01/21/2015] [Accepted: 01/28/2015] [Indexed: 11/17/2022] Open
Abstract
Organisms can end up in unfavourable conditions and to survive this they have evolved various strategies. Some organisms, including nematodes, survive unfavourable conditions by undergoing developmental arrest. The model nematode Caenorhabditis elegans has a developmental choice between two larval forms, and it chooses to develop into the arrested dauer larva form in unfavourable conditions (specifically, a lack of food and high population density, indicated by the concentration of a pheromone). Wild C. elegans isolates vary extensively in their dauer larva arrest phenotypes, and this prompts the question of what selective pressures maintain such phenotypic diversity? To investigate this we grew C. elegans in four different environments, consisting of different combinations of cues that can induce dauer larva development: two combinations of food concentration (high and low) in the presence or absence of a dauer larva-inducing pheromone. Five generations of artificial selection of dauer larvae resulted in an overall increase in dauer larva formation in most selection regimes. The presence of pheromone in the environment selected for twice the number of dauer larvae, compared with environments not containing pheromone. Further, only a high food concentration environment containing pheromone increased the plasticity of dauer larva formation. These evolutionary responses also affected the timing of the worms’ reproduction. Overall, these results give an insight into the environments that can select for different plasticities of C. elegans dauer larva arrest phenotypes, suggesting that different combinations of environmental cues can select for the diversity of phenotypically plastic responses seen in C. elegans.
Collapse
Affiliation(s)
- S Anaid Diaz
- School of Biological Sciences, University of Bristol Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Mark Viney
- School of Biological Sciences, University of Bristol Tyndall Avenue, Bristol, BS8 1TQ, UK
| |
Collapse
|
65
|
Bose N, Meyer JM, Yim JJ, Mayer MG, Markov GV, Ogawa A, Schroeder FC, Sommer RJ. Natural variation in dauer pheromone production and sensing supports intraspecific competition in nematodes. Curr Biol 2015; 24:1536-41. [PMID: 24980503 DOI: 10.1016/j.cub.2014.05.045] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 04/16/2014] [Accepted: 05/16/2014] [Indexed: 11/25/2022]
Abstract
Dauer formation, a major nematode survival strategy, represents a model for small-molecule regulation of metazoan development [1-10]. Free-living nematodes excrete dauer-inducing pheromones that have been assumed to target conspecifics of the same genotype [9, 11]. However, recent studies in Pristionchus pacificus revealed that the dauer pheromone of some strains affects conspecifics of other genotypes more strongly than individuals of the same genotype [12]. To elucidate the mechanistic basis for this intriguing cross-preference, we compared six P. pacificus wild isolates to determine the chemical composition of their dauer-inducing metabolomes and responses to individual pheromone components. We found that these isolates produce dauer pheromone blends of different composition and respond differently to individual pheromone components. Strikingly, there is no correlation between production of and dauer response to a specific compound in individual strains. Specifically, pheromone components that are abundantly produced by one genotype induce dauer formation in other genotypes, but not necessarily in the abundant producer. Furthermore, some genotypes respond to pheromone components they do not produce themselves. These results support a model of intraspecific competition in nematode dauer formation. Indeed, we observed intraspecific competition among sympatric strains in a novel experimental assay, suggesting a new role of small molecules in nematode ecology.
Collapse
Affiliation(s)
- Neelanjan Bose
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Jan M Meyer
- Department for Evolutionary Biology, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Joshua J Yim
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA; Department for Evolutionary Biology, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Melanie G Mayer
- Department for Evolutionary Biology, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Gabriel V Markov
- Department for Evolutionary Biology, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Akira Ogawa
- Department for Evolutionary Biology, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany; Laboratory for Developmental Dynamics, RIKEN Quantitative Biology Center, Kobe 6500047, Japan
| | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
| | - Ralf J Sommer
- Department for Evolutionary Biology, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany.
| |
Collapse
|
66
|
Schroeder FC. Modular assembly of primary metabolic building blocks: a chemical language in C. elegans. CHEMISTRY & BIOLOGY 2015; 22:7-16. [PMID: 25484238 PMCID: PMC4304883 DOI: 10.1016/j.chembiol.2014.10.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 10/12/2014] [Accepted: 10/15/2014] [Indexed: 01/10/2023]
Abstract
The metabolome of the nematode Caenorhabditis elegans, like that of other model organisms, remained largely uncharacterized until recent studies demonstrated the importance of small molecule-based signaling cascades for many aspects of nematode biology. These studies revealed that nematodes are amazingly skilled chemists: using simple building blocks from primary metabolism and a strategy of modular assembly, nematodes create complex molecular architectures that serve as signaling molecules. These nematode-derived modular metabolites (NDMMs) are based on the dideoxysugars ascarylose and paratose, which serve as scaffolds for the attachment of moieties from lipid, amino acid, neurotransmitter, and nucleoside metabolism. Although preliminary biosynthetic studies have confirmed the primary metabolism origin of some of the building blocks incorporated into NDMMs, the mechanisms that underlie their highly specific assembly are not understood. I argue that identification of new variants of primary metabolism-derived structures that serve important signaling functions in C. elegans and other nematodes provides a strong incentive for a comprehensive reanalysis of metabolism in higher animals, including humans.
Collapse
Affiliation(s)
- Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
| |
Collapse
|
67
|
Avery L. A model of the effect of uncertainty on the C elegans L2/L2d decision. PLoS One 2014; 9:e100580. [PMID: 25029446 PMCID: PMC4100763 DOI: 10.1371/journal.pone.0100580] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 05/24/2014] [Indexed: 12/17/2022] Open
Abstract
At the end of the first larval stage, the C elegans larva chooses between two developmental pathways, an L2 committed to reproductive development and an L2d, which has the option of undergoing reproductive development or entering the dauer diapause. I develop a quantitative model of this choice using mathematical tools developed for pricing financial options. The model predicts that the optimal decision must take into account not only the expected potential for reproductive growth, but also the uncertainty in that expected potential. Because the L2d has more flexibility than the L2, it is favored in unpredictable environments. I estimate that the ability to take uncertainty into account may increase reproductive value by as much as 5%, and discuss possible experimental tests for this ability.
Collapse
Affiliation(s)
- Leon Avery
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia, United States of America
- * E-mail:
| |
Collapse
|
68
|
Stoltzfus JD, Bart SM, Lok JB. cGMP and NHR signaling co-regulate expression of insulin-like peptides and developmental activation of infective larvae in Strongyloides stercoralis. PLoS Pathog 2014; 10:e1004235. [PMID: 25010340 PMCID: PMC4092141 DOI: 10.1371/journal.ppat.1004235] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 05/21/2014] [Indexed: 01/18/2023] Open
Abstract
The infectious form of the parasitic nematode Strongyloides stercoralis is a developmentally arrested third-stage larva (L3i), which is morphologically similar to the developmentally arrested dauer larva in the free-living nematode Caenorhabditis elegans. We hypothesize that the molecular pathways regulating C. elegans dauer development also control L3i arrest and activation in S. stercoralis. This study aimed to determine the factors that regulate L3i activation, with a focus on G protein-coupled receptor-mediated regulation of cyclic guanosine monophosphate (cGMP) pathway signaling, including its modulation of the insulin/IGF-1-like signaling (IIS) pathway. We found that application of the membrane-permeable cGMP analog 8-bromo-cGMP potently activated development of S. stercoralis L3i, as measured by resumption of feeding, with 85.1 ± 2.2% of L3i feeding in 200 µM 8-bromo-cGMP in comparison to 0.6 ± 0.3% in the buffer diluent. Utilizing RNAseq, we examined L3i stimulated with DMEM, 8-bromo-cGMP, or the DAF-12 nuclear hormone receptor (NHR) ligand Δ7-dafachronic acid (DA)--a signaling pathway downstream of IIS in C. elegans. L3i stimulated with 8-bromo-cGMP up-regulated transcripts of the putative agonistic insulin-like peptide (ILP) -encoding genes Ss-ilp-1 (20-fold) and Ss-ilp-6 (11-fold) in comparison to controls without stimulation. Surprisingly, we found that Δ7-DA similarly modulated transcript levels of ILP-encoding genes. Using the phosphatidylinositol-4,5-bisphosphate 3-kinase inhibitor LY294002, we demonstrated that 400 nM Δ7-DA-mediated activation (93.3 ± 1.1% L3i feeding) can be blocked using this IIS inhibitor at 100 µM (7.6 ± 1.6% L3i feeding). To determine the tissues where promoters of ILP-encoding genes are active, we expressed promoter::egfp reporter constructs in transgenic S. stercoralis post-free-living larvae. Ss-ilp-1 and Ss-ilp-6 promoters are active in the hypodermis and neurons and the Ss-ilp-7 promoter is active in the intestine and a pair of head neurons. Together, these data provide evidence that cGMP and DAF-12 NHR signaling converge on IIS to regulate S. stercoralis L3i activation.
Collapse
Affiliation(s)
- Jonathan D. Stoltzfus
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Hollins University, Roanoke, Virginia, United States of America
| | - Stephen M. Bart
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America
| | - James B. Lok
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America
| |
Collapse
|
69
|
Chute CD, Srinivasan J. Chemical mating cues in C. elegans. Semin Cell Dev Biol 2014; 33:18-24. [PMID: 24977334 DOI: 10.1016/j.semcdb.2014.06.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 05/14/2014] [Accepted: 06/03/2014] [Indexed: 10/25/2022]
Abstract
In the natural environment it is vital that organisms are capable of locating mates to reproduce and, consequently, increase the diversity of their gene pool. Many species make use of audio and visual communication for mate location. However, the more ancient form of chemical communication is used by all forms of life, from bacteria to mammals. In the past decade, much information has been discovered regarding pheromones in the nematode Caenorhabditis elegans. In this review, chemical signals that govern mating behavior in C. elegans will be discussed, from the existence and identification of mating cues, to the neurons involved in the behavioral response. Specifically, mate attraction is dictated by specific glycosides and side chains of the dideoxysugar ascarylose, a class of molecules known as ascarosides. Intriguingly, modifications of the ascarosides can dictate different behaviors such as male attraction, hermaphrodite attraction, and dauer formation. In general, interactions between core sensory neurons such as ASK and sex-specific neurons like CEM are critical for detecting these small molecules. These data reveal the existence of a complex, synergistic, chemical mating cue system between males and hermaphrodites in C. elegans, thereby highlighting the importance of mate attraction in a primarily hermaphroditic population.
Collapse
Affiliation(s)
- Christopher D Chute
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Life Science and Bioengineering Center, Gateway, Park, 60 Prescott Street, Worcester, MA 01605, United States
| | - Jagan Srinivasan
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Life Science and Bioengineering Center, Gateway, Park, 60 Prescott Street, Worcester, MA 01605, United States.
| |
Collapse
|
70
|
Zhao L, Mota M, Vieira P, Butcher RA, Sun J. Interspecific communication between pinewood nematode, its insect vector, and associated microbes. Trends Parasitol 2014; 30:299-308. [DOI: 10.1016/j.pt.2014.04.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/08/2014] [Accepted: 04/11/2014] [Indexed: 01/23/2023]
|
71
|
Diaz SA, Brunet V, Lloyd-Jones GC, Spinner W, Wharam B, Viney M. Diverse and potentially manipulative signalling with ascarosides in the model nematode C. elegans. BMC Evol Biol 2014; 14:46. [PMID: 24618411 PMCID: PMC4007702 DOI: 10.1186/1471-2148-14-46] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 02/25/2014] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Animals use environmental information to make developmental decisions to maximise their fitness. The nematode Caenorhabditis elegans measures its environment to decide between arresting development as dauer larvae or continuing to grow and reproduce. Worms are thought to use ascarosides as signals of population density and this signalling is thought to be a species-wide honest signal. We compared recently wild C. elegans lines' dauer larva arrest when presented with the same ascaroside signals and in different food environments. RESULTS We find that the hitherto canonical dauer larva response does not hold among these lines. Ascaroside molecules can, depending on the food environment, both promote and repress dauer larva formation. Further, these recently wild C. elegans lines also produce ascaroside mixtures that induce a wide diversity of dauer larva formation responses. We further find that the lines differ in the quantity and ratios of ascaroside molecules that they release. Some of the dauer larva formation responses are consistent with dishonest signalling. CONCLUSIONS Together, the results suggest that the idea that dauer larva formation is an honestly-signalled C. elegans-wide effect does not hold. Rather, the results suggest that ascaroside-based signalling is a public broadcast information system, but where the correct interpretation of that information depends on the worms' context, and is a system open to dishonest signalling.
Collapse
Affiliation(s)
- Sylvia Anaid Diaz
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
- Present Address: School of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Vincent Brunet
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK
| | - Guy C Lloyd-Jones
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK
| | - William Spinner
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
| | - Barney Wharam
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
| | - Mark Viney
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
| |
Collapse
|
72
|
Flatt T, Amdam GV, Kirkwood TBL, Omholt SW. Life-history evolution and the polyphenic regulation of somatic maintenance and survival. QUARTERLY REVIEW OF BIOLOGY 2013; 88:185-218. [PMID: 24053071 DOI: 10.1086/671484] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Here we discuss life-history evolution from the perspective of adaptive phenotypic plasticity, with a focus on polyphenisms for somatic maintenance and survival. Polyphenisms are adaptive discrete alternative phenotypes that develop in response to changes in the environment. We suggest that dauer larval diapause and its associated adult phenotypes in the nematode (Caenorhabditis elegans), reproductive dormancy in the fruit fly (Drosophila melanogaster) and other insects, and the worker castes of the honey bee (Apis mellifera) are examples of what may be viewed as the polyphenic regulation of somatic maintenance and survival. In these and other cases, the same genotype can--depending upon its environment--express either of two alternative sets of life-history phenotypes that differ markedly with respect to somatic maintenance, survival ability, and thus life span. This plastic modulation of somatic maintenance and survival has traditionally been underappreciated by researchers working on aging and life history. We review the current evidence for such adaptive life-history switches and their molecular regulation and suggest that they are caused by temporally and/or spatially varying, stressful environments that impose diversifying selection, thereby favoring the evolution of plasticity of somatic maintenance and survival under strong regulatory control. By considering somatic maintenance and survivorship from the perspective of adaptive life-history switches, we may gain novel insights into the mechanisms and evolution of aging.
Collapse
Affiliation(s)
- Thomas Flatt
- Institut für Populationsgenetik, Vetmeduni Vienna, A-1210 Vienna, Austria.
| | | | | | | |
Collapse
|
73
|
The dauer hypothesis and the evolution of parasitism: 20 years on and still going strong. Int J Parasitol 2013; 44:1-8. [PMID: 24095839 DOI: 10.1016/j.ijpara.2013.08.004] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 08/19/2013] [Accepted: 08/21/2013] [Indexed: 01/31/2023]
Abstract
How any complex trait has evolved is a fascinating question, yet the evolution of parasitism among the nematodes is arguably one of the most arresting. How did free-living nematodes cross that seemingly insurmountable evolutionary chasm between soil dwelling and survival inside another organism? Which of the many finely honed responses to the varied and harsh environments of free-living nematodes provided the material upon which natural selection could act? Although several complementary theories explain this phenomenon, I will focus on the dauer hypothesis. The dauer hypothesis posits that the arrested third-stage dauer larvae of free-living nematodes such as Caenorhabditis elegans are, due to their many physiological similarities with infective third-stage larvae of parasitic nematodes, a pre-adaptation to parasitism. If so, then a logical extension of this hypothesis is that the molecular pathways which control entry into and recovery from dauer formation by free-living nematodes in response to environmental cues have been co-opted to control the processes of infective larval arrest and activation in parasitic nematodes. The molecular machinery that controls dauer entry and exit is present in a wide range of parasitic nematodes. However, the developmental outputs of the different pathways are both conserved and divergent, not only between populations of C. elegans or between C. elegans and parasitic nematodes but also between different species of parasitic nematodes. Thus the picture that emerges is more nuanced than originally predicted and may provide insights into the evolution of such an interesting and complex trait.
Collapse
|
74
|
Density dependence in Caenorhabditis larval starvation. Sci Rep 2013; 3:2777. [PMID: 24071624 PMCID: PMC3784960 DOI: 10.1038/srep02777] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 09/10/2013] [Indexed: 01/15/2023] Open
Abstract
Availability of food is often a limiting factor in nature. Periods of food abundance are followed by times of famine, often in unpredictable patterns. Reliable information about the environment is a critical ingredient of successful survival strategy. One way to improve accuracy is to integrate information communicated by other organisms. To test whether such exchange of information may play a role in determining starvation survival strategies, we studied starvation of L1 larvae in C. elegans and other Caenorhabditis species. We found that some species in genus Caenorhabditis, including C. elegans, survive longer when starved at higher densities, while for others survival is independent of the density. The density effect is mediated by chemical signal(s) that worms release during starvation. This starvation survival signal is independent of ascarosides, a class of small molecules widely used in chemical communication of C. elegans and other nematodes.
Collapse
|
75
|
Abstract
Availability of food is often a limiting factor in nature. Periods of food abundance are followed by times of famine, often in unpredictable patterns. Reliable information about the environment is a critical ingredient of successful survival strategy. One way to improve accuracy is to integrate information communicated by other organisms. To test whether such exchange of information may play a role in determining starvation survival strategies, we studied starvation of L1 larvae in C. elegans and other Caenorhabditis species. We found that some species in genus Caenorhabditis, including C. elegans, survive longer when starved at higher densities, while for others survival is independent of the density. The density effect is mediated by chemical signal(s) that worms release during starvation. This starvation survival signal is independent of ascarosides, a class of small molecules widely used in chemical communication of C. elegans and other nematodes.
Collapse
Affiliation(s)
- Alexander B Artyukhin
- 1] Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA [2] Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA 23298, USA
| | | | | |
Collapse
|
76
|
Ihara S, Yoshikawa K, Touhara K. Chemosensory signals and their receptors in the olfactory neural system. Neuroscience 2013; 254:45-60. [PMID: 24045101 DOI: 10.1016/j.neuroscience.2013.08.063] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 08/29/2013] [Indexed: 11/25/2022]
Abstract
Chemical communication is widely used among various organisms to obtain essential information from their environment required for life. Although a large variety of molecules have been shown to act as chemical cues, the molecular and neural basis underlying the behaviors elicited by these molecules has been revealed for only a limited number of molecules. Here, we review the current knowledge regarding the signaling molecules whose flow from receptor to specific behavior has been characterized. Discussing the molecules utilized by mice, insects, and the worm, we focus on how each organism has optimized its reception system to suit its living style. We also highlight how the production of these signaling molecules is regulated, an area in which considerable progress has been recently made.
Collapse
Affiliation(s)
- S Ihara
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan; ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo 113-8657, Japan
| | | | | |
Collapse
|
77
|
Ascaroside activity in Caenorhabditis elegans is highly dependent on chemical structure. Bioorg Med Chem 2013; 21:5754-69. [PMID: 23920482 DOI: 10.1016/j.bmc.2013.07.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Revised: 07/01/2013] [Accepted: 07/09/2013] [Indexed: 01/26/2023]
Abstract
The nematode Caenorhabditis elegans secretes ascarosides, structurally diverse derivatives of the 3,6-dideoxysugar ascarylose, and uses them in chemical communication. At high population densities, specific ascarosides, which are together known as the dauer pheromone, trigger entry into the stress-resistant dauer larval stage. In order to study the structure-activity relationships for the ascarosides, we synthesized a panel of ascarosides and tested them for dauer-inducing activity. This panel includes a number of natural ascarosides that were detected in crude pheromone extract, but as yet have no assigned function, as well as many unnatural ascaroside derivatives. Most of these ascarosides, some of which have significant structural similarity to the natural dauer pheromone components, have very little dauer-inducing activity. Our results provide a primer to ascaroside structure-activity relationships and suggest that slight modifications to ascaroside structure dramatically influence binding to the relevant G protein-coupled receptors that control dauer formation.
Collapse
|
78
|
Kim KY, Joo HJ, Kwon HW, Kim H, Hancock WS, Paik YK. Development of a Method to Quantitate Nematode Pheromone for Study of Small-Molecule Metabolism in Caenorhabditis elegans. Anal Chem 2013; 85:2681-8. [DOI: 10.1021/ac4001964] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
| | | | | | | | - William S. Hancock
- Barnett Institute, Department
of Chemistry, Northeastern University,
Boston, Massachusetts, United States
| | | |
Collapse
|
79
|
Physiological control of germline development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 757:101-31. [PMID: 22872476 DOI: 10.1007/978-1-4614-4015-4_5] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The intersection between developmental programs and environmental conditions that alter physiology is a growing area of research interest. The C. elegans germ line is emerging as a particularly sensitive and powerful model for these studies. The germ line is subject to environmentally regulated diapause points that allow worms to withstand harsh conditions both prior to and after reproduction commences. It also responds to more subtle changes in physiological conditions. Recent studies demonstrate that different aspects of germ line development are sensitive to environmental and physiological changes and that conserved signaling pathways such as the AMPK, Insulin/IGF, TGFβ, and TOR-S6K, and nuclear hormone receptor pathways mediate this sensitivity. Some of these pathways genetically interact with but appear distinct from previously characterized mechanisms of germline cell fate control such as Notch signaling. Here, we review several aspects of hermaphrodite germline development in the context of "feasting," "food-limited," and "fasting" conditions. We also consider connections between lifespan, metabolism and the germ line, and we comment on special considerations for examining germline development under altered environmental and physiological conditions. Finally, we summarize the major outstanding questions in the field.
Collapse
|
80
|
Neal SJ, Kim K, Sengupta P. Quantitative assessment of pheromone-induced Dauer formation in Caenorhabditis elegans. Methods Mol Biol 2013; 1068:273-83. [PMID: 24014369 DOI: 10.1007/978-1-62703-619-1_20] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Environmental conditions experienced during early larval stages dictate the developmental trajectory of the nematode C. elegans. Favorable conditions such as low population density, abundant food, and lower temperatures allow reproductive growth, while stressful conditions promote entry of second-stage (L2) larvae into the alternate dauer developmental stage. Population density is signaled by the concentration and composition of a complex mixture of small molecules that is produced by all stages of animals, and is collectively referred to as dauer pheromone; pheromone concentration is a major trigger for dauer formation. Here, we describe a quantitative dauer formation assay that provides a measure of the potency of single or mixtures of pheromone components in regulating this critical developmental decision.
Collapse
Affiliation(s)
- Scott J Neal
- Department of Biology, Brandeis University, Waltham, MA, USA
| | | | | |
Collapse
|
81
|
Roy JS, Poulson-Ellestad KL, Drew Sieg R, Poulin RX, Kubanek J. Chemical ecology of the marine plankton. Nat Prod Rep 2013; 30:1364-79. [DOI: 10.1039/c3np70056a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|
82
|
Zhang X, Noguez JH, Zhou Y, Butcher RA. Analysis of ascarosides from Caenorhabditis elegans using mass spectrometry and NMR spectroscopy. Methods Mol Biol 2013; 1068:71-92. [PMID: 24014355 DOI: 10.1007/978-1-62703-619-1_6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The nematode Caenorhabditis elegans secretes a family of water-soluble small molecules, known as the ascarosides, into its environment and uses these ascarosides in chemical communication. The ascarosides are derivatives of the 3,6-dideoxysugar ascarylose, modified with different fatty acid-derived side chains. C. elegans uses specific ascarosides, which are together known as the dauer pheromone, to trigger entry into the stress-resistant dauer larval stage. In addition, C. elegans uses specific ascarosides to control certain behaviors, including mating attraction, aggregation, and avoidance. Although in general the concentration of the ascarosides in the environment increases with population density, C. elegans can vary the types and amounts of ascarosides that it secretes depending on the culture conditions under which it has been grown and its developmental history. Here, we describe how to grow high-density worm cultures and the bacterial food for those cultures, as well as how to extract the culture medium to generate a crude pheromone extract. Then, we discuss how to analyze the types and amounts of ascarosides in that extract using mass spectrometry and NMR spectroscopy.
Collapse
Affiliation(s)
- Xinxing Zhang
- Department of Chemistry, University of Florida, Gainesville, FL, USA
| | | | | | | |
Collapse
|
83
|
Nematode-trapping fungi eavesdrop on nematode pheromones. Curr Biol 2012; 23:83-6. [PMID: 23246407 DOI: 10.1016/j.cub.2012.11.035] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 11/19/2012] [Accepted: 11/19/2012] [Indexed: 12/18/2022]
Abstract
The recognition of molecular patterns associated with specific pathogens or food sources is fundamental to ecology and plays a major role in the evolution of predator-prey relationships. Recent studies showed that nematodes produce an evolutionarily highly conserved family of small molecules, the ascarosides, which serve essential functions in regulating nematode development and behavior. Here, we show that nematophagous fungi, natural predators of soil-dwelling nematodes, can detect and respond to ascarosides. Nematophagous fungi use specialized trapping devices to catch and consume nematodes, and previous studies demonstrated that most fungal species do not produce traps constitutively but rather initiate trap formation in response to their prey. We found that ascarosides, which are constitutively secreted by many species of soil-dwelling nematodes, represent a conserved molecular pattern used by nematophagous fungi to detect prey and trigger trap formation. Ascaroside-induced morphogenesis is conserved in several closely related species of nematophagous fungi and occurs only under nutrient-deprived conditions. Our results demonstrate that microbial predators eavesdrop on chemical communication among their metazoan prey to regulate morphogenesis, providing a striking example of predator-prey coevolution. We anticipate that these findings will have broader implications for understanding other interkingdom interactions involving nematodes, which are found in almost any ecological niche on Earth.
Collapse
|
84
|
Sex-specific mating pheromones in the nematode Panagrellus redivivus. Proc Natl Acad Sci U S A 2012; 109:20949-54. [PMID: 23213209 DOI: 10.1073/pnas.1218302109] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nematodes use an extensive chemical language based on glycosides of the dideoxysugar ascarylose for developmental regulation (dauer formation), male sex attraction, aggregation, and dispersal. However, no examples of a female- or hermaphrodite-specific sex attractant have been identified to date. In this study, we investigated the pheromone system of the gonochoristic sour paste nematode Panagrellus redivivus, which produces sex-specific attractants of the opposite sex. Activity-guided fractionation of the P. redivivus exometabolome revealed that males are strongly attracted to ascr#1 (also known as daumone), an ascaroside previously identified from Caenorhabditis elegans hermaphrodites. Female P. redivivus are repelled by high concentrations of ascr#1 but are specifically attracted to a previously unknown ascaroside that we named dhas#18, a dihydroxy derivative of the known ascr#18 and an ascaroside that features extensive functionalization of the lipid-derived side chain. Targeted profiling of the P. redivivus exometabolome revealed several additional ascarosides that did not induce strong chemotaxis. We show that P. redivivus females, but not males, produce the male-attracting ascr#1, whereas males, but not females, produce the female-attracting dhas#18. These results show that ascaroside biosynthesis in P. redivivus is highly sex-specific. Furthermore, the extensive side chain functionalization in dhas#18, which is reminiscent of polyketide-derived natural products, indicates unanticipated biosynthetic capabilities in nematodes.
Collapse
|
85
|
Jang H, Kim K, Neal SJ, Macosko E, Kim D, Butcher RA, Zeiger DM, Bargmann CI, Sengupta P. Neuromodulatory state and sex specify alternative behaviors through antagonistic synaptic pathways in C. elegans. Neuron 2012; 75:585-92. [PMID: 22920251 DOI: 10.1016/j.neuron.2012.06.034] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2012] [Indexed: 12/14/2022]
Abstract
Pheromone responses are highly context dependent. For example, the C. elegans pheromone ascaroside C9 (ascr#3) is repulsive to wild-type hermaphrodites, attractive to wild-type males, and usually neutral to "social" hermaphrodites with reduced activity of the npr-1 neuropeptide receptor gene. We show here that these distinct behavioral responses arise from overlapping push-pull circuits driven by two classes of pheromone-sensing neurons. The ADL sensory neurons detect C9 and, in wild-type hermaphrodites, drive C9 repulsion through their chemical synapses. In npr-1 mutant hermaphrodites, C9 repulsion is reduced by the recruitment of a gap junction circuit that antagonizes ADL chemical synapses. In males, ADL sensory responses are diminished; in addition, a second pheromone-sensing neuron, ASK, antagonizes C9 repulsion. The additive effects of these antagonistic circuit elements generate attractive, repulsive, or neutral pheromone responses. Neuronal modulation by circuit state and sex, and flexibility in synaptic output pathways, may permit small circuits to maximize their adaptive behavioral outputs.
Collapse
Affiliation(s)
- Heeun Jang
- Howard Hughes Medical Institute and Laboratory of Neural Circuits and Behavior, The Rockefeller University, New York, NY 10065, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
86
|
Noguez JH, Conner ES, Zhou Y, Ciche TA, Ragains JR, Butcher RA. A novel ascaroside controls the parasitic life cycle of the entomopathogenic nematode Heterorhabditis bacteriophora. ACS Chem Biol 2012; 7:961-6. [PMID: 22444073 DOI: 10.1021/cb300056q] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Entomopathogenic nematodes survive in the soil as stress-resistant infective juveniles that seek out and infect insect hosts. Upon sensing internal host cues, the infective juveniles regurgitate bacterial pathogens from their gut that ultimately kill the host. Inside the host, the nematode develops into a reproductive adult and multiplies until unknown cues trigger the accumulation of infective juveniles. Here, we show that the entomopathogenic nematode Heterorhabditis bacteriophora uses a small-molecule pheromone to control infective juvenile development. The pheromone is structurally related to the dauer pheromone ascarosides that the free-living nematode Caenorhabditis elegans uses to control its development. However, none of the C. elegans ascarosides are effective in H. bacteriophora, suggesting that there is a high degree of species specificity. Our report is the first to show that ascarosides are important regulators of development in a parasitic nematode species. An understanding of chemical signaling in parasitic nematodes may enable the development of chemical tools to control these species.
Collapse
Affiliation(s)
- Jaime H. Noguez
- Department of Chemistry, University of Florida, Gainesville, Florida, United States
| | - Elizabeth S. Conner
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana, United States
| | - Yue Zhou
- Department of Chemistry, University of Florida, Gainesville, Florida, United States
| | - Todd A. Ciche
- Department of Microbiology and
Molecular Genetics, Michigan State University, East Lansing, Michigan, United States
| | - Justin R. Ragains
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana, United States
| | - Rebecca A. Butcher
- Department of Chemistry, University of Florida, Gainesville, Florida, United States
| |
Collapse
|
87
|
Kaplan F, Alborn HT, von Reuss SH, Ajredini R, Ali JG, Akyazi F, Stelinski LL, Edison AS, Schroeder FC, Teal PE. Interspecific nematode signals regulate dispersal behavior. PLoS One 2012; 7:e38735. [PMID: 22701701 PMCID: PMC3368880 DOI: 10.1371/journal.pone.0038735] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 05/09/2012] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Dispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2) of plant parasitic Meloidogyne spp. and infective juveniles (IJ)s of entomopathogenic nematodes (EPN), e.g., Steinernema feltiae. Regulation of dispersal behavior has not been thoroughly investigated for C. elegans or any other nematode species. Based on the fact that ascarosides regulate entry in dauer stage as well as multiple behaviors in C. elegans adults including mating, avoidance and aggregation, we hypothesized that ascarosides might also be involved in regulation of dispersal behavior in C. elegans and for other nematodes such as IJ of phylogenetically related EPNs. METHODOLOGY/PRINCIPAL FINDINGS Liquid chromatography-mass spectrometry analysis of C. elegans dauer conditioned media, which shows strong dispersing activity, revealed four known ascarosides (ascr#2, ascr#3, ascr#8, icas#9). A synthetic blend of these ascarosides at physiologically relevant concentrations dispersed C. elegans dauer in the presence of food and also caused dispersion of IJs of S. feltiae and J2s of plant parasitic Meloidogyne spp. Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9) and C. elegans (ascr#2) dispersal blends. Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers. CONCLUSIONS/SIGNIFICANCE Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.
Collapse
Affiliation(s)
- Fatma Kaplan
- Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Gainesville, Florida, United States of America.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
88
|
Interaction of structure-specific and promiscuous G-protein-coupled receptors mediates small-molecule signaling in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2012; 109:9917-22. [PMID: 22665789 DOI: 10.1073/pnas.1202216109] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A chemically diverse family of small-molecule signals, the ascarosides, control developmental diapause (dauer), olfactory learning, and social behaviors of the nematode model organism, Caenorhabditis elegans. The ascarosides act upstream of conserved signaling pathways, including the insulin, TGF-β, serotonin, and guanylyl cyclase pathways; however, the sensory processes underlying ascaroside function are poorly understood. Because ascarosides often are multifunctional and show strongly synergistic effects, characterization of their receptors will be essential for understanding ascaroside biology and may provide insight into molecular mechanisms that produce synergistic outcomes in small-molecule sensing. Based on DAF-8 immunoprecipitation, we here identify two G-protein-coupled receptors, DAF-37 and DAF-38, which cooperatively mediate ascaroside perception. daf-37 mutants are defective in all responses to ascr#2, one of the most potent dauer-inducing ascarosides, although this mutant responds normally to other ascarosides. In contrast, daf-38 mutants are partially defective in responses to several different ascarosides. Through cell-specific overexpression, we show that DAF-37 regulates dauer when expressed in ASI neurons and adult behavior when expressed in ASK neurons. Using a photoaffinity-labeled ascr#2 probe and amplified luminescence assays (AlphaScreen), we demonstrate that ascr#2 binds to DAF-37. Photobleaching fluorescent energy transfer assays revealed that DAF-37 and DAF-38 form heterodimers, and we show that heterodimerization strongly increases cAMP inhibition in response to ascr#2. These results suggest that that the ascarosides' intricate signaling properties result in part from the interaction of highly structure-specific G-protein-coupled receptors such as DAF-37 with more promiscuous G-protein-coupled receptors such as DAF-38.
Collapse
|
89
|
|
90
|
Abstract
Larvae of the nematode Caenorhabditis elegans must choose between reproductive development and dauer diapause. This decision is based on sensing of environmental inputs and dauer pheromone, a small molecule signal that serves to monitor population density. These signals are integrated via conserved neuroendocrine pathways that converge on steroidal ligands of the nuclear receptor DAF-12, a homolog of the mammalian vitamin D receptor and liver X receptor. DAF-12 acts as the main switch between gene expression programs that drive either reproductive development or dauer entry. Extensive studies in the past two decades demonstrated that biosynthesis of two bile acid-like DAF-12 ligands, named dafachronic acids (DA), controls developmental fate. In this issue of PLoS Biology, Wollam et al. showed that a conserved steroid-modifying enzyme, DHS-16, introduces a key feature in the structures of the DAF-12 ligands, closing a major gap in the DA biosynthesis pathway. The emerging picture of DA biosynthesis in C. elegans enables us to address a key question in the field: how are complex environmental signals integrated to enforce binary, organism-wide decisions on developmental fate? Schaedel et al. demonstrated that pheromone and DA serve as competing signals, and that a positive feedback loop based on regulation of DA biosynthesis ensures organism-wide commitment to reproductive development. Considering that many components of DA signaling are highly conserved, ongoing studies in C. elegans may reveal new aspects of bile acid function and lifespan regulation in mammals.
Collapse
Affiliation(s)
- Siu Sylvia Lee
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
- * E-mail: (SSL); (FCS)
| | - Frank C. Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
- * E-mail: (SSL); (FCS)
| |
Collapse
|
91
|
Abstract
Phenotypic plasticity refers to the ability of an organism to adopt different phenotypes depending on environmental conditions. In animals and plants, the progression of juvenile development and the formation of dormant stages are often associated with phenotypic plasticity, indicating the importance of phenotypic plasticity for life-history theory. Phenotypic plasticity has long been emphasized as a crucial principle in ecology and as facilitator of phenotypic evolution. In nematodes, several examples of phenotypic plasticity have been studied at the genetic and developmental level. In addition, the influence of different environmental factors has been investigated under laboratory conditions. These studies have provided detailed insight into the molecular basis of phenotypic plasticity and its ecological and evolutionary implications. Here, we review recent studies on the formation of dauer larvae in Caenorhabditis elegans, the evolution of nematode parasitism and the generation of a novel feeding trait in Pristionchus pacificus. These examples reveal a conserved and co-opted role of an endocrine signaling module involving the steroid hormone dafachronic acid. We will discuss how hormone signaling might facilitate life-history and morphological evolution.
Collapse
|
92
|
von Reuss SH, Bose N, Srinivasan J, Yim JJ, Judkins JC, Sternberg PW, Schroeder FC. Comparative metabolomics reveals biogenesis of ascarosides, a modular library of small-molecule signals in C. elegans. J Am Chem Soc 2012; 134:1817-24. [PMID: 22239548 PMCID: PMC3269134 DOI: 10.1021/ja210202y] [Citation(s) in RCA: 151] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the model organism Caenorhabditis elegans, a family of endogenous small molecules, the ascarosides function as key regulators of developmental timing and behavior that act upstream of conserved signaling pathways. The ascarosides are based on the dideoxysugar ascarylose, which is linked to fatty-acid-like side chains of varying lengths derived from peroxisomal β-oxidation. Despite the importance of ascarosides for many aspects of C. elegans biology, knowledge of their structures, biosynthesis, and homeostasis remains incomplete. We used an MS/MS-based screen to profile ascarosides in C. elegans wild-type and mutant metabolomes, which revealed a much greater structural diversity of ascaroside derivatives than previously reported. Comparison of the metabolomes from wild-type and a series of peroxisomal β-oxidation mutants showed that the enoyl CoA-hydratase MAOC-1 serves an important role in ascaroside biosynthesis and clarified the functions of two other enzymes, ACOX-1 and DHS-28. We show that, following peroxisomal β-oxidation, the ascarosides are selectively derivatized with moieties of varied biogenetic origin and that such modifications can dramatically affect biological activity, producing signaling molecules active at low femtomolar concentrations. Based on these results, the ascarosides appear as a modular library of small-molecule signals, integrating building blocks from three major metabolic pathways: carbohydrate metabolism, peroxisomal β-oxidation of fatty acids, and amino acid catabolism. Our screen further demonstrates that ascaroside biosynthesis is directly affected by nutritional status and that excretion of the final products is highly selective.
Collapse
Affiliation(s)
- Stephan H. von Reuss
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Neelanjan Bose
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Jagan Srinivasan
- Howard Hughes Medical Institute and Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
| | - Joshua J. Yim
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Joshua C. Judkins
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Paul W. Sternberg
- Howard Hughes Medical Institute and Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
| | - Frank C. Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| |
Collapse
|
93
|
McGrath PT, Xu Y, Ailion M, Garrison JL, Butcher RA, Bargmann CI. Parallel evolution of domesticated Caenorhabditis species targets pheromone receptor genes. Nature 2011; 477:321-5. [PMID: 21849976 PMCID: PMC3257054 DOI: 10.1038/nature10378] [Citation(s) in RCA: 172] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 07/20/2011] [Indexed: 11/15/2022]
Abstract
Evolution can follow predictable genetic trajectories1, indicating that discrete environmental shifts can select for reproducible genetic changes2-4. Conspecific individuals are an important feature of an animal's environment, and a potential source of selective pressures. We show here that adaptation of two Caenorhabditis species to growth at high density, a feature common to domestic environments, occurs by reproducible genetic changes to pheromone receptor genes. Chemical communication through pheromones that accumulate during high-density growth causes young nematode larvae to enter the long-lived but non-reproductive dauer stage. Two strains of Caenorhabditis elegans grown at high density have independently acquired multigenic resistance to pheromone-induced dauer formation. In each strain, resistance to the pheromone ascaroside C3 results from a deletion that disrupts the adjacent chemoreceptor genes serpentine receptor class g (srg)-36 and -37. Through misexpression experiments, we show that these genes encode redundant G protein-coupled receptors for ascaroside C3. Multigenic resistance to dauer formation has also arisen in high-density cultures of a different nematode species, Caenorhabditis briggsae, resulting in part from deletion of an srg gene paralogous to srg-36 and srg-37. These results demonstrate rapid remodeling of the chemoreceptor repertoire as an adaptation to specific environments, and indicate that parallel changes to a common genetic substrate can affect life history traits across species.
Collapse
Affiliation(s)
- Patrick T McGrath
- Howard Hughes Medical Institute, Laboratory of Neural Circuits and Behavior, The Rockefeller University, New York, New York 10065, USA
| | | | | | | | | | | |
Collapse
|
94
|
Hulme SE, Whitesides GM. Die Chemie und der Wurm: Caenorhabditis elegans als Plattform für das Zusammenführen von chemischer und biologischer Forschung. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201005461] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
95
|
Hulme SE, Whitesides GM. Chemistry and the Worm: Caenorhabditis elegans as a Platform for Integrating Chemical and Biological Research. Angew Chem Int Ed Engl 2011; 50:4774-807. [DOI: 10.1002/anie.201005461] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Indexed: 12/15/2022]
|
96
|
Kaplan F, Srinivasan J, Mahanti P, Ajredini R, Durak O, Nimalendran R, Sternberg PW, Teal PEA, Schroeder FC, Edison AS, Alborn HT. Ascaroside expression in Caenorhabditis elegans is strongly dependent on diet and developmental stage. PLoS One 2011; 6:e17804. [PMID: 21423575 PMCID: PMC3058051 DOI: 10.1371/journal.pone.0017804] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Accepted: 02/11/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The ascarosides form a family of small molecules that have been isolated from cultures of the nematode Caenorhabditis elegans. They are often referred to as "dauer pheromones" because most of them induce formation of long-lived and highly stress resistant dauer larvae. More recent studies have shown that ascarosides serve additional functions as social signals and mating pheromones. Thus, ascarosides have multiple functions. Until now, it has been generally assumed that ascarosides are constitutively expressed during nematode development. METHODOLOGY/PRINCIPAL FINDINGS Cultures of C. elegans were developmentally synchronized on controlled diets. Ascarosides released into the media, as well as stored internally, were quantified by LC/MS. We found that ascaroside biosynthesis and release were strongly dependent on developmental stage and diet. The male attracting pheromone was verified to be a blend of at least four ascarosides, and peak production of the two most potent mating pheromone components, ascr#3 and asc#8 immediately preceded or coincided with the temporal window for mating. The concentration of ascr#2 increased under starvation conditions and peaked during dauer formation, strongly supporting ascr#2 as the main population density signal (dauer pheromone). After dauer formation, ascaroside production largely ceased and dauer larvae did not release any ascarosides. These findings show that both total ascaroside production and the relative proportions of individual ascarosides strongly correlate with these compounds' stage-specific biological functions. CONCLUSIONS/SIGNIFICANCE Ascaroside expression changes with development and environmental conditions. This is consistent with multiple functions of these signaling molecules. Knowledge of such differential regulation will make it possible to associate ascaroside production to gene expression profiles (transcript, protein or enzyme activity) and help to determine genetic pathways that control ascaroside biosynthesis. In conjunction with findings from previous studies, our results show that the pheromone system of C. elegans mimics that of insects in many ways, suggesting that pheromone signaling in C. elegans may exhibit functional homology also at the sensory level. In addition, our results provide a strong foundation for future behavioral modeling studies.
Collapse
Affiliation(s)
- Fatma Kaplan
- Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, Gainesville, Florida, United States of America
| | - Jagan Srinivasan
- Medical Institute and Biology Division, California Institute of Technology, Pasadena, California, United States of America
| | - Parag Mahanti
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - Ramadan Ajredini
- Department of Biochemistry and Molecular Biology, High Magnetic Field Laboratory, University of Florida, Gainesville, Florida, United States of America
| | - Omer Durak
- Medical Institute and Biology Division, California Institute of Technology, Pasadena, California, United States of America
| | - Rathika Nimalendran
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - Paul W. Sternberg
- Medical Institute and Biology Division, California Institute of Technology, Pasadena, California, United States of America
| | - Peter E. A. Teal
- Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, Gainesville, Florida, United States of America
| | - Frank C. Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - Arthur S. Edison
- Department of Biochemistry and Molecular Biology, High Magnetic Field Laboratory, University of Florida, Gainesville, Florida, United States of America
| | - Hans T. Alborn
- Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, Gainesville, Florida, United States of America
- * E-mail:
| |
Collapse
|
97
|
Robinette SL, Ajredini R, Rasheed H, Zeinomar A, Schroeder FC, Dossey AT, Edison AS. Hierarchical alignment and full resolution pattern recognition of 2D NMR spectra: application to nematode chemical ecology. Anal Chem 2011; 83:1649-57. [PMID: 21314130 PMCID: PMC3066641 DOI: 10.1021/ac102724x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Nuclear magnetic resonance (NMR) is the most widely used nondestructive technique in analytical chemistry. In recent years, it has been applied to metabolic profiling due to its high reproducibility, capacity for relative and absolute quantification, atomic resolution, and ability to detect a broad range of compounds in an untargeted manner. While one-dimensional (1D) (1)H NMR experiments are popular in metabolic profiling due to their simplicity and fast acquisition times, two-dimensional (2D) NMR spectra offer increased spectral resolution as well as atomic correlations, which aid in the assignment of known small molecules and the structural elucidation of novel compounds. Given the small number of statistical analysis methods for 2D NMR spectra, we developed a new approach for the analysis, information recovery, and display of 2D NMR spectral data. We present a native 2D peak alignment algorithm we term HATS, for hierarchical alignment of two-dimensional spectra, enabling pattern recognition (PR) using full-resolution spectra. Principle component analysis (PCA) and partial least squares (PLS) regression of full resolution total correlation spectroscopy (TOCSY) spectra greatly aid the assignment and interpretation of statistical pattern recognition results by producing back-scaled loading plots that look like traditional TOCSY spectra but incorporate qualitative and quantitative biological information of the resonances. The HATS-PR methodology is demonstrated here using multiple 2D TOCSY spectra of the exudates from two nematode species: Pristionchus pacificus and Panagrellus redivivus. We show the utility of this integrated approach with the rapid, semiautomated assignment of small molecules differentiating the two species and the identification of spectral regions suggesting the presence of species-specific compounds. These results demonstrate that the combination of 2D NMR spectra with full-resolution statistical analysis provides a platform for chemical and biological studies in cellular biochemistry, metabolomics, and chemical ecology.
Collapse
Affiliation(s)
- Steven L Robinette
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610-0245, United States
| | | | | | | | | | | | | |
Collapse
|
98
|
Lee J, Kim KY, Joo HJ, Kim H, Jeong PY, Paik YK. Methods for Evaluating the Caenorhabditis elegans Dauer State: Standard Dauer-Formation Assay Using Synthetic Daumones and Proteomic Analysis of O-GlcNAc Modifications. Methods Cell Biol 2011; 106:445-60. [PMID: 22118287 DOI: 10.1016/b978-0-12-544172-8.00016-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
|
99
|
Mulcahy B, Ient B. Meeting report: 2010 Caenorhabditis elegans Neurobiology Meeting, University of Wisconsin, USA. INVERTEBRATE NEUROSCIENCE 2010; 10:53-61. [PMID: 21069413 DOI: 10.1007/s10158-010-0110-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Accepted: 10/26/2010] [Indexed: 10/18/2022]
Abstract
Against the backdrop of the scenic Lake Mendota, the C. elegans Neurobiology Meeting came to a head. Expertly organised by Brian Ackley and Bruce Bamber and hosted at the accommodating University of Wisconsin, the meeting brought together recent contributions from many of the major research groups working on the neurobiology of C. elegans. With seven keynote speakers, 57 verbal presentations and hundreds of posters, this exciting event spanned a fascinating 3 days from 27 June to 30 June 2010. In keeping with the tradition of this conference, the event on the whole was spearheaded by young investigators from several research institutions. The meeting served to emphasise the gains enjoyed by taking advantage of the genetic tractability of the worm. A thread that ran through the meeting was the importance of integrating data across different levels of biological organisation to permit delineation of the physiology underpinning discrete behavioural states. Recent advances in optogenetics and microfluidics were at the forefront of refining these analyses. The presentations discussed in this meeting report are a selection which reflects this overarching theme.
Collapse
Affiliation(s)
- Ben Mulcahy
- School of Biological Sciences, University of Southampton, Building 85, Highfield Campus, Southampton SO17 1BJ, UK.
| | | |
Collapse
|
100
|
Garrity PA, Goodman MB, Samuel AD, Sengupta P. Running hot and cold: behavioral strategies, neural circuits, and the molecular machinery for thermotaxis in C. elegans and Drosophila. Genes Dev 2010; 24:2365-82. [PMID: 21041406 PMCID: PMC2964747 DOI: 10.1101/gad.1953710] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Like other ectotherms, the roundworm Caenorhabditis elegans and the fruit fly Drosophila melanogaster rely on behavioral strategies to stabilize their body temperature. Both animals use specialized sensory neurons to detect small changes in temperature, and the activity of these thermosensors governs the neural circuits that control migration and accumulation at preferred temperatures. Despite these similarities, the underlying molecular, neuronal, and computational mechanisms responsible for thermotaxis are distinct in these organisms. Here, we discuss the role of thermosensation in the development and survival of C. elegans and Drosophila, and review the behavioral strategies, neuronal circuits, and molecular networks responsible for thermotaxis behavior.
Collapse
Affiliation(s)
- Paul A. Garrity
- Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA
- National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Miriam B. Goodman
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305, USA
| | - Aravinthan D. Samuel
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Piali Sengupta
- Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA
- National Center for Behavioral Genomics, Brandeis University, Waltham, Massachusetts 02454, USA
| |
Collapse
|